Hybrid power system of quayside container crane and control method

Abstract

The embodiment of the invention provides a hybrid power system of a quayside container crane and a control method, and relates to the technical field of hybrid power of quayside container cranes. The problems that due to the large power requirement of the quayside container crane, the power cannot be adapted when the hybrid power technology is applied, and the battery parallel connection risk is large are solved. The system comprises a DC bus, a bidirectional rectifier, a plurality of frequency converters, a plurality of charging and discharging branches and a control system. The plurality of charging and discharging branches are physically isolated and connected in parallel to the direct current bus, each charging and discharging branch comprises a battery pack and a bidirectional direct current converter, and the control system is used for calculating the distribution power of the single charging and discharging branch according to the real-time quay crane power requirement and the number of the online charging and discharging branches. The hybrid power control method for the quayside container crane is used for controlling the system, the distribution power of a single charging and discharging branch is accurately calculated through the real-time quayside crane power requirement and the number of online charging and discharging branches, and balanced charging and discharging between battery packs are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of hybrid power for shore container cranes, and in particular to a hybrid power system and a control method for shore container cranes. Background Art

[0002] Hybrid technology in container terminals is generally used on yard cranes and horizontal mobile equipment powered by traditional internal combustion engines, such as rubber-tyred gantry cranes, automated guided vehicles, and straddle carriers, among other container handling equipment. Since the installed power of these devices is generally below 400 kW, they are well-suited to the energy density of current mature lithium battery solutions, and thus hybrid technology has been widely used in this type of equipment. However, as core equipment with a single unit power exceeding 2000 kW, quay cranes have high installed power and a high number of loading and unloading operations per unit time. Users have concerns about the use of such high-power battery technology in a single unit, and therefore there are currently no examples of hybrid quay crane applications. However, for container terminals in some underdeveloped countries or regions, which often face the difficult situation of underdeveloped local power grids and weak power supply capabilities, hybrid quay cranes remain an urgent need.

[0003] The power requirement of a single quay crane is typically more than four times that of a hybrid electric gantry crane. To apply mature gantry crane battery technology to gantry cranes, a similar number of batteries must be connected in parallel to achieve the required power output. The maximum allowable current of each battery cell in this parallel configuration is far less than the gantry crane's operating current, resulting in uneven current distribution and localized battery overload, which can lead to thermal runaway or lifespan degradation. Existing passive gantry crane balancing technology is slow to respond and inefficient, and cannot meet the millisecond-level power response requirements of gantry cranes.

[0004] Quay crane operating loads fluctuate dramatically. For example, peak lifting power can be several times higher than continuous operation, and multiple operating modes are involved, including no-load movement, fully loaded lifting, and regenerative braking. The discreteness of battery pack parameters is further amplified under dynamic loads, leading to chronic overcharge and over-discharge of some units, threatening system safety. Summary of the Invention

[0005] The following is a brief summary of one or more aspects to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceivable aspects and is neither intended to identify key or critical elements of all aspects nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that will be provided later.

[0006] The objectives of the present invention include, for example, providing a hybrid power system for a shore container crane, which can improve the problems of high power demand of shore container cranes, such as the inability to adapt the power when applying hybrid power technology, and the high risk of parallel connection of batteries.

[0007] The purpose of the present invention also includes providing a hybrid power control method for a shore container crane, which can improve the problem that the shore container crane has high power demand, resulting in the inability to adapt to the power and the high risk of parallel connection of batteries when applying hybrid power technology.

[0008] The embodiments of the present invention can be implemented as follows:

[0009] An embodiment of the present invention provides a hybrid power system for a shore container crane, comprising a DC bus, a bidirectional rectifier, multiple frequency converters, multiple charging and discharging branches, and a control system; the AC side of the bidirectional rectifier is connected to a main power supply, and the DC side of the bidirectional rectifier is connected to the DC bus; the DC side of each frequency converter is connected to the DC bus, and the AC side of each frequency converter is connected to a drive motor of a shore crane; the multiple charging and discharging branches are physically isolated and connected in parallel to the DC bus, each charging and discharging branch comprises a battery pack and a bidirectional DC converter, the low-voltage side of the bidirectional DC converter is connected to the corresponding battery pack, and the high-voltage side of the bidirectional DC converter is connected to the DC bus; the bidirectional rectifier, the frequency converter, the battery pack, and the bidirectional DC converter are all communicatively connected to the control system, and the control system is used to calculate the allocated power of a single charging and discharging branch based on the real-time shore crane power demand and the number of online charging and discharging branches, and the control system is also used to control the bidirectional DC converter to operate according to the allocated power.

[0010] In addition, the hybrid system for the shore container crane provided by the embodiment of the present invention may also have the following additional technical features:

[0011] Optionally, the control system includes a quay crane main control system and a battery management system controller; the battery management system controller, the bidirectional rectifier and the frequency converter are respectively communicated with the quay crane main control system; all bidirectional DC converters and the battery management systems inside all battery packs are respectively communicated with the battery management system controller.

[0012] Optionally, after the multiple bidirectional DC converters on the multiple charging and discharging branches are communicated and connected in sequence, they are communicated and connected to the battery management system controller; the battery management system controller designates one of the bidirectional DC converters as the master converter, and the remaining bidirectional DC converters as slave converters; the master converter is used to receive the power allocation instructions of the battery management system controller and synchronize them to all slave converters; the slave converters are used to synchronously execute the power instructions of the master converter.

[0013] Optionally, when the operating condition requirement of the quay crane changes, the control system is used to calculate the number of the charging and discharging branches according to the operating condition requirement of the quay crane.

[0014] Optionally, in the event that a single charge and discharge branch fails, the control system is configured to control the failed charge and discharge branch to be disconnected, and recalculate the power allocation value according to the number of remaining charge and discharge branches.

[0015] Optionally, during the quay crane energy feedback stage, the control system is used to distribute the regenerated electric energy in proportion to each of the charging and discharging branches for charging.

[0016] Optionally, when the quay crane is in standby mode, the control system is used to control the bidirectional DC converter to pre-charge each battery pack with a small current, and to make all battery packs reach the same capacity.

[0017] An embodiment of the present invention further provides a hybrid power control method for a shore container crane, which is used to control a hybrid power system of a shore container crane, comprising:

[0018] In standby pre-charging mode, each bidirectional DC converter is controlled to pre-charge the battery pack with a constant low current until all battery packs reach the same capacity;

[0019] When the quay crane is in operation, the power demand signal of the quay crane is obtained in real time, and the allocated power of a single charging and discharging branch is calculated based on the number of online charging and discharging branches;

[0020] According to the calculated distributed power, the power instructions are synchronized to all the bidirectional DC converters.

[0021] Optionally, the hybrid power control method for the shore container crane further includes:

[0022] The power allocated to a single charging and discharging branch = the real-time power demand of the quay crane / the number of online charging and discharging branches.

[0023] Optionally, the hybrid power control method for the shore container crane further includes:

[0024] When a faulty charging and discharging branch is detected, it is immediately isolated and the allocated power is updated based on the number of remaining charging and discharging branches.

[0025] The beneficial effects of the hybrid power system and control method of the shore container crane according to the embodiments of the present invention include, for example:

[0026] The hybrid power system of a shore container crane includes a DC bus, a bidirectional rectifier, multiple frequency converters, multiple charging and discharging branches, and a control system; the AC side of the bidirectional rectifier is connected to the main power supply, and the DC side of the bidirectional rectifier is connected to the DC bus; the DC side of each frequency converter is connected to the DC bus, and the AC side of each frequency converter is connected to the drive motor of the shore crane; the multiple charging and discharging branches are physically isolated and connected in parallel to the DC bus, each charging and discharging branch includes a battery pack and a bidirectional DC converter, the low-voltage side of the bidirectional DC converter is connected to the corresponding battery pack, and the high-voltage side of the bidirectional DC converter is connected to the DC bus; the bidirectional rectifier, frequency converter, battery pack, and bidirectional DC converter are all communicatively connected to the control system, and the control system is used to calculate the allocated power of a single charging and discharging branch based on the real-time shore crane power demand and the number of online charging and discharging branches. The control system is also used to control the bidirectional DC converter to operate according to the allocated power.

[0027] By connecting multiple groups of charging and discharging branches that are physically isolated from each other and can be independently controlled in parallel, the high-power demand of the quay crane is decomposed into multiple small-power branches. Based on the real-time quay crane power demand and the number of online charging and discharging branches, the distributed power of a single charging and discharging branch is accurately calculated, and the bidirectional DC converter is controlled to operate accordingly, achieving balanced charging and discharging between battery groups and reliable operation of the high-power hybrid quay crane.

[0028] The hybrid power control method for a shore container crane is used to control the above-mentioned system, thereby improving the problem that the shore container crane has high power demand, resulting in the inability to adapt to the power and the high risk of parallel connection of batteries when applying hybrid power technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above features and advantages of the present invention will be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or characteristics may have the same or similar reference numerals.

[0030] Figure 1 A framework diagram of a hybrid power system for a shore container crane provided in an embodiment of the present invention.

[0031] Icons: quay crane main control system-100; battery management system controller-200; main power supply-300; motor-400; bidirectional rectifier-500; inverter-600; bidirectional DC converter-700; battery pack-800. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Note that the various aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention.

[0033] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inner", "outer", "vertical" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when in use, rather than indicating or implying that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0034] At the same time, it should be noted that the terms "first", "second", etc. are only used to distinguish and describe, and cannot be understood as indicating or implying relative importance.

[0035] It should also be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connection, integral connection, or detachable connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0036] The following combination Figure 1 The hybrid power system of the shore container crane provided in this embodiment is described in detail.

[0037] Please refer to Figure 1 An embodiment of the present invention provides a hybrid power system for a shore container crane, comprising a DC bus, a bidirectional rectifier 500, multiple frequency converters 600, multiple charge and discharge branches, and a control system; the AC side of the bidirectional rectifier 500 is connected to a main power supply 300, and the DC side of the bidirectional rectifier 500 is connected to the DC bus; the DC side of each frequency converter 600 is connected to the DC bus, and the AC side of each frequency converter 600 is connected to a drive motor 400 of a shore crane; the multiple charge and discharge branches are physically isolated and connected in parallel to the DC bus, and each charge and discharge branch includes The bidirectional DC converter 700 includes a battery pack 800 and a bidirectional DC converter 700. The low-voltage side of the bidirectional DC converter 700 is connected to the corresponding battery pack 800, and the high-voltage side of the bidirectional DC converter 700 is connected to the DC bus. The bidirectional rectifier 500, the inverter 600, the battery pack 800 and the bidirectional DC converter 700 are all communicatively connected to the control system. The control system is used to calculate the allocated power of a single charging and discharging branch based on the real-time shore crane power demand and the number of online charging and discharging branches. The control system is also used to control the bidirectional DC converter 700 to operate according to the allocated power.

[0038] It should be noted that the DC bus is connected to all devices that generate (supply) and consume (use) electricity. Electricity flows and exchanges at high speeds on this bus in the form of direct current (DC). The voltage is typically maintained at a constant value, such as 720 VDC in this example.

[0039] The main power source 300, typically the grid or a diesel generator 400, is connected to the DC bus via a bidirectional rectifier 500. This provides the primary source of alternating current (AC). When the grid power supply is stable, it is the primary energy source for the quay crane.

[0040] The bidirectional rectifier 500, with its input connected to the main power supply 300 and its output connected to the DC bus, is used for rectification (AC->DC), converting the AC power from the main power supply 300 into DC power, which is then supplied to the DC bus and drives the various quay crane mechanisms. It also performs inversion (DC->AC). When the DC bus voltage is excessively high due to feedback energy from the quay crane (such as when a mechanism lowers a heavy object), the excess DC power is inverted into AC power, which is then fed back to the main power supply 300 (if the grid permits) or consumed (e.g., by connecting to a braking resistor). It stabilizes the bus voltage and is one of the key components for maintaining a constant DC bus voltage.

[0041] The inverter 600 has its input connected to the DC bus and its output connected to the corresponding motors 400, such as the hoist motor 400, trolley motor 400, and carriage motor 400. Its functions include inversion (DC to AC), converting the DC power on the DC bus into AC power of a specific frequency and voltage, precisely controlling the speed and torque of each motor 400 to drive the quay crane for loading and unloading. It also performs rectification (AC to DC), converting the AC power generated by the motors 400 into DC power when the motors 400 are generating electricity (such as when lowering a load or braking a mechanism). This power is then fed back to the DC bus.

[0042] The electric motors are indirectly connected to the DC bus via the corresponding inverter 600. They perform specific operations of the quay crane (lifting / lowering containers, moving trolleys, and moving large vehicles). They are the main consumers of electricity (in the motoring state) and also potential providers of electricity (in the generating state).

[0043] The hybrid power system for the quayside container crane achieves efficient operation through a unique design. A bidirectional rectifier 500 connects the main power supply 300 to the DC bus, enabling bidirectional conversion and transmission of electrical energy. A frequency converter 600 connects the DC bus to the drive motor 400, flexibly adjusting the motor's operation. Multiple physically isolated charging and discharging branches are connected in parallel to the DC bus. The battery pack 800, in conjunction with the bidirectional DC converter 700, enables flexible charging and discharging. The control system, at its core, accurately calculates the power allocation for each charging and discharging branch based on the real-time quayside crane power demand and the number of online charging and discharging branches, and controls the bidirectional DC converter 700 accordingly. This system dynamically adjusts power distribution based on actual operating conditions, improving energy efficiency and reducing energy consumption. This system also enhances system stability and reliability, effectively handling the complex power fluctuations during quayside crane operations and ensuring efficient and stable equipment operation.

[0044] Reference Figure 1 In this embodiment, a quayside container crane (hereinafter referred to as a "quay crane") hybrid power system utilizing multiple controllable branches is proposed to meet the application requirements of quayside container crane hybrid power. This system connects multiple physically isolated and independently controllable charging and discharging branches in parallel, breaking down the high power demand of the quayside container crane into multiple smaller branches. This system also ensures balanced charging and discharging of the lithium batteries, enabling reliable operation of the high-power hybrid quayside container crane.

[0045] Reference Figure 1 In this embodiment, the control system includes a quay crane main control system 100 and a battery management system controller 200; the battery management system controller 200, the bidirectional rectifier 500 and the inverter 600 are respectively communicated with the quay crane main control system 100; all bidirectional DC converters 700 and the battery management systems inside all battery packs 800 are respectively communicated with the battery management system controller 200.

[0046] The main control system 100 of the quay crane is Figure 1 The main PLC in the battery management system controller 200, that is, Figure 1 The battery PLC in the quay crane system. The quay crane main control system 100 serves as the "brain," communicating with the battery management system controller 200, bidirectional rectifier 500, and inverter 600. It coordinates the overall situation and issues appropriate commands based on the quay crane's operating conditions. The battery management system controller 200 focuses on the battery pack 800 and connects to the bidirectional DC converter 700 and the battery's internal management system to precisely control battery charging and discharging. This seamless integration of all components allows for flexible power allocation based on real-time demand, improving energy efficiency, ensuring stable operation of the quay crane, and reducing the probability of failure.

[0047] Reference Figure 1In this embodiment, multiple bidirectional DC converters 700 on multiple charging and discharging branches are sequentially connected to each other and then connected to the battery management system controller 200. The battery management system controller 200 designates one bidirectional DC converter 700 as a master converter and the remaining bidirectional DC converters 700 as slave converters. The master converter is used to receive power allocation instructions from the battery management system controller 200 and synchronize them to all slave converters. The slave converters are used to synchronously execute the power instructions of the master converter.

[0048] The bidirectional DC converters 700 on multiple charging and discharging branches utilize this master-slave communication connection, resulting in significant technical benefits. The battery management system controller 200, also known as the battery PLC, directs the master and slave converters via the communication network, ensuring that the multiple independent charging and discharging branches function as a coordinated whole, providing high-power, reliable, and balanced hybrid power support for the quay crane. Faults in any charging and discharging branch can be isolated, and the system automatically adjusts the remaining branches to continue operation.

[0049] After designating the master and slave converters, the battery management system controller 200 simply sends power allocation instructions to the master converter, which then synchronizes these instructions to all slave converters. This greatly simplifies the communication process, reduces the complexity and error probability of command transmission, and improves system response speed. The slave converters synchronously execute the master converter's instructions, ensuring that the bidirectional DC converters 700 on each charging and discharging branch operate in unison and work in coordination, achieving precise power distribution and unified control. This not only improves the overall stability and reliability of the operation of multiple charging and discharging branches, but also effectively avoids power conflicts or uneven distribution that may result from the independent operation of each converter, thereby optimizing the performance of the entire hybrid power system and enabling more efficient and stable operation during shore container crane operations.

[0050] Reference Figure 1 In this embodiment, when the operating requirements of the quay crane change, the control system is used to calculate the number of charging and discharging branches according to the operating requirements of the quay crane.

[0051] As the quay crane's operating requirements change, the control system accurately calculates the number of charging and discharging branches based on these changes. This design offers significant advantages. When the operating conditions increase the power demand, the control system increases the number of charging and discharging branches, quickly providing more power to meet the quay crane's heavy load requirements and avoid power shortages that affect operational efficiency. If the operating conditions decrease, the number of branches decreases, reducing unnecessary power loss and achieving energy savings. This dynamic adjustment method optimizes the system's energy utilization, improves the quay crane's adaptability and operational stability under different operating conditions, and ensures efficient and economical operations.

[0052] Reference Figure 1In this embodiment, when a single charge and discharge branch fails, the control system is used to control the faulty charge and discharge branch to be disconnected, and recalculate the power allocation value according to the number of remaining charge and discharge branches.

[0053] When a single charging / discharging branch fails, the control system quickly disconnects it, effectively isolating the fault and preventing it from spreading and affecting the entire hybrid system, ensuring the continued safe operation of the rest of the system. Subsequently, the power distribution value is recalculated based on the number of remaining charging / discharging branches, allowing the remaining branches to appropriately share the power originally borne by the faulty branch, ensuring that the quay crane still receives a stable and appropriate power supply and maintains operational continuity. This rapid and precise process significantly reduces the disruption to quay crane operations caused by the fault, improves system reliability and stability, and reduces downtime losses caused by the fault.

[0054] Reference Figure 1 In this embodiment, during the energy feedback stage of the quay crane, the control system is used to distribute the regenerated electric energy to each charging and discharging branch in proportion.

[0055] During the quay crane's energy recovery phase, the control system proportionally distributes regenerative power to each charging and discharging branch, a significant improvement. This proportional distribution rationally plans the amount of power received based on the actual status and capacity of each charging and discharging branch, preventing damage to individual branches due to overcharging and extending the service life of the battery pack 800. Furthermore, balanced charging distribution allows all branches to participate in energy recovery, improving the efficiency of regenerative power utilization and reducing energy waste. Furthermore, this orderly charging method ensures the stability of the system charging process, enabling efficient and stable operation of the quay crane during the energy recovery phase and reducing the risk of failure.

[0056] Reference Figure 1 In this embodiment, when the quay crane is in standby mode, the control system is used to control the bidirectional DC converter 700 to pre-charge each battery pack 800 with a small current, and to make all the battery packs 800 reach the same capacity.

[0057] When the quay crane is in standby mode, the control system directs the bidirectional DC converter 700 to pre-charge each battery pack 800 with a low current and equalize their capacities, achieving significant results. This low-current pre-charging prevents damage to the battery packs 800 from high current surges, effectively protecting the batteries and extending their service life. Equalizing the capacities of all battery packs 800 ensures that, during subsequent operations, each battery pack 800 can be charged and discharged synchronously and evenly, preventing overcharging or over-discharging of some batteries due to capacity differences and improving the overall performance and stability of the battery packs 800. This not only enhances the reliability of the quay crane hybrid system, but also reduces maintenance costs and ensures a stable energy supply during quay crane operations.

[0058] An embodiment of the present invention also provides a hybrid power control method for a shore container crane, which is used to control a hybrid power system of a shore container crane, including: in the standby pre-charging state, controlling each bidirectional DC converter 700 to pre-charge the battery pack 800 with a constant small current until all battery packs 800 reach the same capacity; when the shore crane is in operation, obtaining the power demand signal of the shore crane in real time, and calculating the distributed power of a single charging and discharging branch based on the number of online charging and discharging branches; based on the calculated distributed power, synchronizing the power command to all bidirectional DC converters 700.

[0059] During standby pre-charging, the battery pack 800 is charged at a constant low current until the capacity reaches the same level. This avoids high-current surges, protects the batteries, extends their lifespan, and ensures balanced subsequent charging and discharging. During quay crane operation, the system acquires power demand signals in real time and calculates power allocation based on the number of online charging and discharging branches, optimizing power distribution. This power command is then synchronized to each bidirectional DC converter 700, ensuring coordinated operation of each branch and accurately responding to power demands. This improves energy efficiency, enhances system stability, and ensures efficient and stable operation of the quayside container crane.

[0060] In this embodiment, the hybrid power control method for the quayside container crane further includes: power allocated to a single charging and discharging branch = real-time power demand of the quayside crane / number of online charging and discharging branches.

[0061] During quay crane operation, real-time power demand constantly changes. This formula dynamically and rationally allocates power to each branch based on the number of online branches. This ensures balanced power distribution among branches when they operate in concert, preventing overloaded or idle branches and improving energy efficiency. Furthermore, balanced power distribution reduces equipment wear and extends service life, ensuring stable and efficient operation of the quayside container crane hybrid system.

[0062] In this embodiment, the hybrid power control method for the shore container crane further includes: immediately isolating a faulty charging and discharging branch when a fault is detected, and updating the allocated power based on the number of remaining charging and discharging branches.

[0063] Upon detection of a faulty charging / discharging branch, immediate isolation can quickly cut off the source of the fault, preventing it from spreading and impacting the entire system, and ensuring the safe operation of other normal branches. Power allocation is updated based on the number of remaining charging / discharging branches, rationally replanning power output based on the actual number of available branches, allowing the remaining branches to continue efficiently and stably providing the required power to the quay crane, maintaining operational continuity. This not only improves system reliability and stability, but also reduces the risk and losses of downtime caused by faults, ensuring the efficient and reliable operation of the quay crane hybrid system.

[0064] Example 1

[0065] The surge power demand of a quay crane is 2000 kW for 3 seconds; the steady-state power demand is 1200 kW for 10 seconds; and the steady-state feedback power is -1000 kW for 10 seconds. The bus voltage is a constant 720 VDC. Each operating cycle consumes 12 kWh of power, with 8 kWh of feedback. The quay crane's operating capacity is calculated based on 40 cycles per hour, 20 hours per day, and 300 days per year. The terminal is located in an area with limited power supply, requiring the design of a lithium battery system to reduce the need for 400 diesel generators.

[0066] 1. Converter selection: A 250kW DC bidirectional converter, 1000V / 250A, with an overload rating of 1.5x, corresponding to a power output of 180kW at a 720V operating voltage. This converter features master-slave control, a maximum parallel connection of eight units, and voltage and current control technology.

[0067] When the power is stable, the number of converters = 1200 / 180 = 6.7, which is an integer of 7.

[0068] When the power is impacted, the number of converters = 2000 / 180 / 1.5 = 7.4, which is an integer of 8.

[0069] Because the number required for impulse power is greater than that for steady power, 8 converters are finally selected in parallel.

[0070] The converter's power output is 180 kW at a corresponding operating voltage of 720 V. For a stable power demand of 1200 kW, 6.7 converters are calculated, rounded up to 7 to meet the stable power demand. For a surge power demand of 2000 kW, accounting for a 1.5-fold overload, 7.4 converters are calculated, rounded up to 8 to meet the surge power demand. This selection comprehensively considers power requirements under different operating conditions, ensuring sufficient power to support the quay crane operation under all operating conditions. Ultimately, eight converters were selected in parallel to handle the higher power demand during surge power conditions, ensuring system stability and reliability under complex operating conditions. The converter features master-slave control, with a maximum parallel connection of eight. This enables multiple converters to work together, achieving unified power distribution and management, improving overall system performance and controllability. Its voltage and current control technology precisely controls bus voltage and charge and discharge currents, ensuring power quality, minimizing damage to batteries and other equipment, and extending equipment life.

[0071] Second, battery selection:

[0072] Select a battery model with 773VDC, 207KWh, a maximum charge and discharge current of 268A, and a cycle life of 4500 cycles. There are 16 groups in total, with two groups connected to each converter.

[0073] Stable operating current calibration: 268*2=536>250A, passed.

[0074] Inrush current correction: 268*2=536>(250*1.5=375)A, passed.

[0075] The 773VDC battery was chosen to closely match the system bus voltage of 720VDC, reducing energy loss during voltage conversion and improving energy efficiency. The battery capacity is 207KWh, and the total capacity of the 16 battery packs is large enough to meet the energy storage and release requirements during quay crane operations, especially during the steady-state power feedback phase, effectively recovering regenerative energy.

[0076] Both the stable operating current and surge current tests passed, indicating that the battery's maximum charge and discharge current can meet the quay crane's current requirements under various operating conditions. During stable operation, the current provided by Battery Pack 800 exceeds the converter's current requirements. During surge conditions, the current provided by Battery Pack 800 also exceeds the converter's overload current requirements, ensuring normal system operation. There are 16 battery packs in total, with two groups connected to each converter. This grouped connection facilitates management and control. The battery pack's charge and discharge strategy can be flexibly adjusted based on different operating conditions and converter operating status, improving system flexibility and reliability.

[0077] 3. Service life estimation:

[0078] The available electricity is 207*16*4500=14904000KWh.

[0079] The annual power consumption of the quay crane is 4*40*20*300=960,000KWh.

[0080] The number of available years is 14904000 / 960000=15.5.

[0081] The available power is 207,164,500 = 14,904,000 kWh. This calculation, based on battery capacity and cycle life, accurately estimates the total power the battery can provide over its entire service life. The annual power consumption of the quay crane is 44,020 * 300 = 960,000 kWh. Based on the power consumption per operating cycle, the number of cycles per hour, the number of operating hours per day, and the number of operating days per year, the calculated annual power consumption is consistent with actual conditions and provides a reliable basis for service life estimation. The usable years are 14,904,000 / 960,000 = 15.5 years. The battery service life is estimated by using the ratio of available power to annual power consumption. This result demonstrates that the selected battery has a long service life while meeting the operational requirements of the quay crane, providing long-term, stable energy support for the terminal and reducing the frequency and cost of battery replacement.

[0082] According to a hybrid power system for a shore container crane provided in this embodiment, the working principle of the hybrid power system for a shore container crane includes:

[0083] exist Figure 1 The upper portion of the DC busbar shows the basic drive configuration for the quay crane. The main power supply 300 is rectified by a bidirectional rectifier 500 and then connected to the DC busbar. The motors 400 of each of the quay crane's drive mechanisms are connected to the DC busbar via their own frequency converters 600. Below the DC busbar, the high-power battery packs adapted to the quay crane's power requirements are divided into multiple smaller battery packs 800, each connected in parallel to the DC busbar via a bidirectional DC converter 700. All bidirectional DC converters 700 implement a master-slave control system, with bidirectional DC converter 700 No. 1 serving as the master converter and the others as slave converters. During quay crane operation, the master converter calculates the current real-time power demand of the quay crane and, based on the number of online converters, calculates the power share required of each converter. The master converter operates according to this power demand, and all slave converters follow the master converter's lead. A battery PLC is connected to all bidirectional DC converters 700 to realize control of the bidirectional DC converters 700; at the same time, the battery PLC performs bidirectional communication with the main PLC of the quay crane to collect the real-time power of the quay crane.

[0084] The operating process of this technology includes the following: When the quay crane is in standby mode, the battery PLC controls the bidirectional DC converter 700 to pre-charge each battery pack 800 with a low current, ensuring that each battery pack reaches the same capacity. When the quay crane is started, the battery PLC receives operating information from the master PLC and calculates the quay crane's power consumption in real time. It then distributes the power evenly based on the current number of battery packs 800 and sends an average power command to the master converter. The master converter then sends the power command synchronously to all slave converters. All master and slave converters operate synchronously to compensate for the quay crane's real-time power. If a battery branch fails, the battery PLC can promptly detect and disconnect the faulty branch. The battery PLC resets the branch count and distributes the quay crane power accordingly.

[0085] The hybrid power system of a shore container crane provided by this embodiment has at least the following advantages:

[0086] The capacity requirement of the quay crane is divided from high power into multiple low power branches working in parallel, achieving power separation. This allows the battery to be configured with the most mature components used by the manufacturer, ensuring the reliability of battery application.

[0087] The use of multiple independent battery branches can achieve physical isolation between battery groups. The failure of any branch will not affect other branches. When any battery group fails, the system can automatically isolate it to keep the quay crane working continuously.

[0088] Each branch is equipped with an independent bidirectional DC converter 700, and all converters implement master-slave control, so that the batteries in each branch can be charged and discharged evenly, reducing the working energy imbalance problem between the battery packs 800 and avoiding overcharging or over-discharging problems in individual branches.

[0089] According to the working conditions of the quay crane, the terminal can flexibly configure the number of parallel branches to meet the required capacity configuration.

[0090] Container terminals can flexibly configure hybrid quay cranes according to operating conditions and ensure that the supporting lithium batteries are in the most mature configuration without being limited by the capacity of the quay crane itself, thereby maximizing the reliability of the hybrid application.

[0091] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technology in this field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A hybrid power system for a shore container crane, characterized in that: include: DC bus; a bidirectional rectifier, wherein the AC side of the bidirectional rectifier is connected to a main power supply, and the DC side of the bidirectional rectifier is connected to the DC bus; A plurality of frequency converters, wherein the DC side of each frequency converter is connected to the DC bus, and the AC side of each frequency converter is connected to the drive motor of the quay crane; Multiple charging and discharging branches, each of which is physically isolated and connected in parallel to the DC bus, each of which includes a battery pack and a bidirectional DC converter, the low-voltage side of the bidirectional DC converter being connected to the corresponding battery pack, and the high-voltage side of the bidirectional DC converter being connected to the DC bus; and a control system, wherein the bidirectional rectifier, the frequency converter, the battery pack and the bidirectional DC converter are all communicatively connected to the control system, the control system is used to calculate the allocated power of a single charging and discharging branch based on the real-time shore crane power demand and the number of online charging and discharging branches, and the control system is also used to control the bidirectional DC converter to operate according to the allocated power.

2. The hybrid power system of the shore container crane according to claim 1, characterized in that: The control system includes a quay crane main control system and a battery management system controller; the battery management system controller, the bidirectional rectifier and the frequency converter are respectively communicated with the quay crane main control system; all bidirectional DC converters and the battery management systems inside all battery packs are respectively communicated with the battery management system controller.

3. The hybrid power system of the shore container crane according to claim 2, characterized in that: After the multiple bidirectional DC converters on the multiple charging and discharging branches are communicated and connected in sequence, they are communicated and connected to the battery management system controller; the battery management system controller designates one of the bidirectional DC converters as the master converter and the remaining bidirectional DC converters as slave converters; the master converter is used to receive the power allocation instructions of the battery management system controller and synchronize them to all slave converters; the slave converters are used to synchronously execute the power instructions of the master converter.

4. The hybrid power system of the shore container crane according to claim 1, characterized in that: When the operating requirements of the quay crane change, the control system is used to calculate the number of the charging and discharging branches according to the operating requirements of the quay crane.

5. The hybrid power system of the shore container crane according to claim 4, characterized in that: In the event of a single charge and discharge branch failing, the control system is configured to disconnect the failed charge and discharge branch and recalculate the power allocation value based on the number of remaining charge and discharge branches.

6. The hybrid power system of the shore container crane according to claim 1, characterized in that: During the energy feedback stage of the quay crane, the control system is used to distribute the regenerated electric energy in proportion to each of the charging and discharging branches for charging.

7. The hybrid power system of a shore container crane according to claim 1, characterized in that: When the quay crane is in standby mode, the control system is used to control the bidirectional DC converter to pre-charge each battery pack with a small current and make all battery packs reach the same capacity.

8. A hybrid power control method for a shore container crane, used to control the hybrid power system of a shore container crane according to any one of claims 1 to 7, characterized in that: include: In standby pre-charging mode, each bidirectional DC converter is controlled to pre-charge the battery pack with a constant low current until all battery packs reach the same capacity; When the quay crane is in operation, the power demand signal of the quay crane is obtained in real time, and the allocated power of a single charging and discharging branch is calculated based on the number of online charging and discharging branches; According to the calculated distributed power, the power instructions are synchronized to all the bidirectional DC converters.

9. The hybrid power control method for a shore container crane according to claim 8, characterized in that: The hybrid power control method for the shore container crane further includes: The power allocated to a single charging and discharging branch = the real-time power demand of the quay crane / the number of online charging and discharging branches.

10. The hybrid power control method for a shore container crane according to claim 8, characterized in that: The hybrid power control method for the shore container crane further includes: When a faulty charging and discharging branch is detected, it is immediately isolated and the allocated power is updated based on the number of remaining charging and discharging branches.

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